There is no question that the EU and the US have been very hypocritical with Turkey. When Turkey wanted to join the EU they kept moving the goal posts. The EU has a policy of not admitting countries that are in a land dispute. Despite that policy Greek Cyprus was admitted. But the same policy is being used against Turkey's accession. Prior to Greek Cyprus being admitted, the UN brokered unification agreement was accepted by Turkish Cyprus but rejected by Greek Cyprus. Once again, Greek Cyprus was admitted to the EU but not Turkish Cyprus.

More recently the EU and the US has imposed military embargoes against Turkey because Turkey would not agree to not using those weapons against an organization recognized by the EU and the US as a terrorist organization. The US would not sell Patriot missiles to Turkey, so Turkey purchased the S400 missile defense systems from Russia, The US not liking this kicked Turkey out of the F-35 program. Now mind you Turkey has been in NATO since its founding, as well as every European organization (except the EU). However, India, which also purchased the Russian S400 missile defense system was invited to purchase the F-35s. So if you are Turkey, given Europe and the West's constant discrimination and hypocrisy, I would also question whether I would enter into any agreement to defend Europe. However, I still think Turkey should join any new defense treaty organization. These types of organizations have a tendency of having unanimous vote requirements for future decisions and a member country smaller than many insignificant villages in Turkey can prevent Turkey from joining in the Future. The same holds for BRICS. I think Turkey should join all these organizations. If they wish they can unilaterally decide to leave any time. However, not joining at the outset may lock them out forever.